The invention relates to a tool interface, i.e. a tool interface for coupling a tool head to a tool shank in a centered manner in respect of a shank axis, according to the preamble of claim 1. Such a tool interface is known from WO 2008/110370 A1.
The tool head is, in particular, a stock-removing tool head, e.g. a drilling, turning, milling, reaming or grinding head. The invention further relates to a tool head or tool shank provided with an associated part of such an interface, and to a tool comprising the tool head, the tool shank and the interface.
There is increasing use of multipart tools, in which the tool head and the tool shank are produced independently of each other and are coupled to each other via an interface of the above-mentioned type. Advantages of multipart tool production as compared with single-piece production of a tool head and tool shank are, in particular, that the tool head, when worn out, can be exchanged independently of the tool shank, and that one and the same shank can be used as a common holder for a plurality of tool heads existing as a set. In both cases, costs of material and production are saved in the use of the tool or of a corresponding tool set. A further advantage of multipart tool production is that the tool head and the tool shank can be produced from differing materials, each particularly well suited to the respective requirements. In particular, frequently the tool head is produced—for cost reasons, inter alia—from a hard, but comparatively brittle sintered metal, while a material that is stable under torsional load, in particular steel or hard metal, is normally selected for the tool shank. The shank in this case, in turn, can be composed of a plurality of parts, which can be of differing materials. The tool head also, in turn, can be a multipart tool head, in particular composed of a carrier having cutting inserts fastened thereon.
A tool interface of the above-mentioned type always consists of two interface parts, of which one is assigned to the tool shank and the other is assigned to the tool head. The shank and head of a tool in this case are usually screw-connected, for which purpose the interface parts have corresponding screw-connection means. In addition, the two interface parts are normally provided with mutually complementary interface surfaces, which are intended to bear flatly on each other and enable the tool to be seated in a precise manner on the shank, in particular centered exactly relative to a shank axis. This is intended, in particular, to prevent concentricity errors in the case of tools operated in rotation.
Often, these interface surfaces are realized as so-called plane-cone surfaces. Such surfaces comprise a conical partial surface and, adjoining the latter, a plane partial surface that is perpendicular to the shank axis, the corresponding interface surfaces bearing on each other in both surface regions when in the mounted state. Such a plane-conical seating requires extremely precise production of the associated interface surfaces, particularly since even small machining errors result an inadequate bearing contact of the interface surfaces, either in the conical or in the plane region. In the case of sintered tool heads, in particular, the required precision of the interface surface is not achievable, or can be achieved only with a large resource input. In particular, the interface surfaces of the head-side interface part in the case of such tool heads normally require resource-consuming reworking, by turning, milling and/or grinding.